S40 T5 won't start - Ignition switch?

[FunkyMelon]

Hi all,

Apparently the recent £1000 spend on my car isn't quite enough.

Last night after work I unlocked the car to go home and it unlocked fine, key in ignition, steering unlocked fine......Position II, lights, radio and electrics come on, position 3, nothing, nada......Won't start.

Checked the battery and that was fine. Did a quick google and grabbed a DMM from work, found the relay for the starter motor and discovered the constant 12V signal was there but the switched positive pin which activates the starter had it's signal missing when ignition III position was on? At this point I got an 'IMMOBILISER SEE MANUAL' message on the dash.

I stuck the relay on a bench supply at work and it's working fine and switching when prodding the correct pins, so that rules the relay out.

After some head scratching, I shorted the switched and constant voltage pins in the fuse box for the relay together, mimicking the signal from the ignition barrel with a friend from work holding the key in ignition III and the engine instantly fired to life!

I met my girlfriend at Volvo and dumped it there at around 8pm with the keys in their letter box, she brought my DICE/VIDA setup so did a quick scan and got 'CEM-1A41 - Ignition switch faulty signal'

This has never happened before, was fine that morning and fine at lunch, now suddenly it doesn't work?

Is this the dreaded SCL/SCU playing up or a CEM fault?

Bloody cars

[LizardOfBodom]

Damn....it does sound like SCU fault, judging by the symptoms :/
You could have tried 2nd key if you have one but I bet it would be the same.

Did you hear the "bzzt" of the steering wheel lock when key was entered?

So now you are waiting for a verdict from stealership?

[FunkyMelon]

Yep, steering unlocks fine, tried my girlfriends key for my car with the same result.

It's at the Volvo my uncle runs thankfully, so he'll only charge what he absolutely has to, so at least that's something, either way, looking like it's gonna cost me again.

It just seems odd that it would suddenly go on me, I'd expect intermittent issues before it going completely.

[LizardOfBodom]

Originally Posted by FunkyMelon

Yep, steering unlocks fine, tried my girlfriends key for my car with the same result.

It's at the Volvo my uncle runs thankfully, so he'll only charge what he absolutely has to, so at least that's something, either way, looking like it's gonna cost me again.

It just seems odd that it would suddenly go on me, I'd expect intermittent issues before it going completely.

I think SCU is one of those things that works binary (either does or not so maybe its just unlucky coincidence. Or maybe something different (hopefully cheaper to fix), let us know, fingers crossed!

[FunkyMelon]

It's the SCU - Doh!

[LizardOfBodom]

Originally Posted by FunkyMelon

It's the SCU - Doh!

Sorry

course of action now?

salvage&program or new SCU?

[FunkyMelon]

Part is £150 something retail with no discount added yet. Hour to fit. No software required

Not too bad at all.

[Clan]

Originally Posted by LizardOfBodom

Sorry

course of action now?

salvage&program or new SCU?

New for sure as they have modified/improved it twice since yours was new ...

[FunkyMelon]

Originally Posted by Clan

New for sure as they have modified/improved it twice since yours was new ...

Over-engineered!

These new XC90's, V60, V90 etc with 130+ computers controlling it are all going to be gigantic money pits in 5+ years.

It's genuinely scary and I'm an electronics/embedded software engineer myself!

[LizardOfBodom]

Originally Posted by FunkyMelon

Part is £150 something retail with no discount added yet. Hour to fit. No software required

Not too bad at all.

No software needed? How come, so what are you actually getting (p. n. )? I had impression that SCU had to be programmed in? Unless its only the physical part with reciever but actual Unit remains as is?

bit confused now